1. Field of the Invention
The present invention relates generally to electronic devices and, more particularly, to programmable power management systems and methods.
2. Related Art
A typical electronic device, which includes one or more printed circuit boards that form a complex electronic system, requires multiple voltages for supplying power to numerous components. For example, the components may include a fan requiring 12 volts (V), memory devices requiring 2.5 V and 1.8 V, a microprocessor requiring 2.5 V and 1.8 V, analog circuits requiring 5 V, and logic devices requiring 5 V, 3.3 V, and 2.5 V. These components may further require a complex power-on or reset sequence that employs a timed, defined, reset signal. Additionally, many of these components cannot tolerate significant voltage swings or a power supply interruption and may require an interrupt or reset signal prior to powering down. Consequently, various portions of the printed circuit board or electronic system may require various voltages and a structured power up, power down, and reset sequence.
Failure to maintain the proper voltage level or to power down correctly may result in problems such as a static random access memory prematurely erasing required data or the entire system locking-up. A watchdog timer circuit may be required in case the system or processor locks-up in order to properly reset the system.
The system may also require thermal management to control the printed circuit board's thermal condition. For example, thermal management may control a fan speed based on temperature readings. Furthermore, the system may require a board level identification tag memory (e.g., a serial electrically erasable programmable read only memory) to identify and track the printed circuit board.
A conventional electronics system may monitor voltages, provide reset signals and power-loss warnings, or provide a watchdog circuit and battery backup switching. However, a drawback of conventional systems is that to perform these functions requires many discrete and specialized integrated circuits, which occupy valuable printed circuit board space. Furthermore, the identification tag memory along with the thermal management circuit, if these are included, are provided as stand-alone devices that occupy additional printed circuit board space and add to the size and complexity of the overall system.
Another drawback of these conventional systems is that generally there is no on-board logic for system control or sequencing. If programmable functions are permitted, it is only provided through resistor/capacitor networks that are external to the power management integrated circuits. Therefore, discrete components are required, additional board space is required, and limited control or options are provided. For example, the voltage, timing, polarity, and input/output signals are generally fixed or have limited versatility.
As a result, there is a need for a single device that will consolidate the functions of the various stand-alone power management devices and provide on-chip programmable functions.